Due to excellent properties such as low electric-power consumption and longer operating life, a light-emitting diode has been brought into service as a luminous source such as a traffic signal, a lighting apparatus or the like. Then, a white light-emitting diode produced by combining a blue light-emitting diode and a yellow light emitter YAG:Ce3+ has been developed and therefore studies on a high-power visible light-emitting diode are underway in many fields (e.g., see Japanese unexamined patent application publication No. 2003-105336).